TI-81 Conic Section Grapher
Public Domain
by Daniel Bishop
http://www.ticalc.org/archives/files/authors/35/3568.html

This program will graph relations of the form AX+BXY+CY+DX+EY+F=0.

Prgm_:CONIC
:Disp "X COEF"
:Input A
:Disp "XY COEF"
:Input B
:Disp "Y COEF"
:Input C
:Disp "X COEF"
:Input D
:Disp "Y COEF"
:Input E
:Disp "CONSTANT"
:Input F
:All-Off
:"(-(BX+E)+sqrt((BX+E)-4C(AX+DX+F)))/2C -> Y3
:"(-(BX+E)-sqrt((BX+E)-4C(AX+DX+F)))/2C -> Y4
:DispGraph